The purpose of this study is to identify psychological, sociological and other factors associated with low rates of immunization and well child care. Mothers enrolled in the study were interviewed shortly after giving birth. This "baseline" interview included information on sociodemographic characteristics of the mother, father and infant; the mothers medical history; psychosocial features of the family; and maternal knowledge, beliefs and practices surrounding well child care and immunizations and other health care practices. Two "follow-up" interviews were conducted, one when the infant was between three and seven months of age and one when the infant was between seven months and one year of age. A number of questions and topics covered on the baseline interview (e.g., perceived social norms regarding immunization practices) were repeated in the three and seven month interviews. Additionally, outcome data on health care practices, medical visits, and immunizations were collected during these "follow-up" interviews. Information obtained in the three and seven month interviews on immunizations and medical visits was verified via inspection of medical records at the identified provider sites. At three months 75% of infants were up to date (UTD) versus only 41% at seven months. Factors associated with being UTD included enrollment in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) during pregnancy, intention to breastfeed, presence of the infant's grandmother in the household, low perceived barriers to immunization, lower birth order, and maternal employment. Results were published in Pediatrics (Pediatrics 2001; 108:661-670). Current analyses are focusing on factors associated with the initiation and duration of breastfeeding and on infant sleep practices.